/*
   *
   * Copyright (C) 2007 Google, Inc.
   * Copyright (c) 2009-2012,2014, The Linux Foundation. All rights reserved.
   *
   * This software is licensed under the terms of the GNU General Public
   * License version 2, as published by the Free Software Foundation, and
   * may be copied, distributed, and modified under those terms.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   */
  
  #include <linux/clocksource.h>
  #include <linux/clockchips.h>
  #include <linux/cpu.h>
  #include <linux/init.h>
  #include <linux/interrupt.h>
  #include <linux/irq.h>
  #include <linux/io.h>
  #include <linux/of.h>
  #include <linux/of_address.h>
  #include <linux/of_irq.h>
  #include <linux/sched_clock.h>
  
  #include <asm/delay.h>
  
  #define TIMER_MATCH_VAL			0x0000
  #define TIMER_COUNT_VAL			0x0004
  #define TIMER_ENABLE			0x0008
  #define TIMER_ENABLE_CLR_ON_MATCH_EN	BIT(1)
  #define TIMER_ENABLE_EN			BIT(0)
  #define TIMER_CLEAR			0x000C
  #define DGT_CLK_CTL			0x10
  #define DGT_CLK_CTL_DIV_4		0x3
  #define TIMER_STS_GPT0_CLR_PEND		BIT(10)
  
  #define GPT_HZ 32768
  
  static void __iomem *event_base;
  static void __iomem *sts_base;
  
  static irqreturn_t msm_timer_interrupt(int irq, void *dev_id)
  {
  	struct clock_event_device *evt = dev_id;
  	/* Stop the timer tick */
  	if (clockevent_state_oneshot(evt)) {
  		u32 ctrl = readl_relaxed(event_base + TIMER_ENABLE);
  		ctrl &= ~TIMER_ENABLE_EN;
  		writel_relaxed(ctrl, event_base + TIMER_ENABLE);
  	}
  	evt->event_handler(evt);
  	return IRQ_HANDLED;
  }
  
  static int msm_timer_set_next_event(unsigned long cycles,
  				    struct clock_event_device *evt)
  {
  	u32 ctrl = readl_relaxed(event_base + TIMER_ENABLE);
  
  	ctrl &= ~TIMER_ENABLE_EN;
  	writel_relaxed(ctrl, event_base + TIMER_ENABLE);
  
  	writel_relaxed(ctrl, event_base + TIMER_CLEAR);
  	writel_relaxed(cycles, event_base + TIMER_MATCH_VAL);
  
  	if (sts_base)
  		while (readl_relaxed(sts_base) & TIMER_STS_GPT0_CLR_PEND)
  			cpu_relax();
  
  	writel_relaxed(ctrl | TIMER_ENABLE_EN, event_base + TIMER_ENABLE);
  	return 0;
  }
  
  static int msm_timer_shutdown(struct clock_event_device *evt)
  {
  	u32 ctrl;
  
  	ctrl = readl_relaxed(event_base + TIMER_ENABLE);
  	ctrl &= ~(TIMER_ENABLE_EN | TIMER_ENABLE_CLR_ON_MATCH_EN);
  	writel_relaxed(ctrl, event_base + TIMER_ENABLE);
  	return 0;
  }
  
  static struct clock_event_device __percpu *msm_evt;
  
  static void __iomem *source_base;
  
  static notrace cycle_t msm_read_timer_count(struct clocksource *cs)
  {
  	return readl_relaxed(source_base + TIMER_COUNT_VAL);
  }
  
  static struct clocksource msm_clocksource = {
  	.name	= "dg_timer",
  	.rating	= 300,
  	.read	= msm_read_timer_count,
  	.mask	= CLOCKSOURCE_MASK(32),
  	.flags	= CLOCK_SOURCE_IS_CONTINUOUS,
  };
  
  static int msm_timer_irq;
  static int msm_timer_has_ppi;
  
  static int msm_local_timer_setup(struct clock_event_device *evt)
  {
  	int cpu = smp_processor_id();
  	int err;
  
  	evt->irq = msm_timer_irq;
  	evt->name = "msm_timer";
  	evt->features = CLOCK_EVT_FEAT_ONESHOT;
  	evt->rating = 200;
  	evt->set_state_shutdown = msm_timer_shutdown;
  	evt->set_state_oneshot = msm_timer_shutdown;
  	evt->tick_resume = msm_timer_shutdown;
  	evt->set_next_event = msm_timer_set_next_event;
  	evt->cpumask = cpumask_of(cpu);
  
  	clockevents_config_and_register(evt, GPT_HZ, 4, 0xffffffff);
  
  	if (msm_timer_has_ppi) {
  		enable_percpu_irq(evt->irq, IRQ_TYPE_EDGE_RISING);
  	} else {
  		err = request_irq(evt->irq, msm_timer_interrupt,
  				IRQF_TIMER | IRQF_NOBALANCING |
  				IRQF_TRIGGER_RISING, "gp_timer", evt);
  		if (err)
  			pr_err("request_irq failed
  ");
  	}
  
  	return 0;
  }
  
  static void msm_local_timer_stop(struct clock_event_device *evt)
  {
  	evt->set_state_shutdown(evt);
  	disable_percpu_irq(evt->irq);
  }
  
  static int msm_timer_cpu_notify(struct notifier_block *self,
  					   unsigned long action, void *hcpu)
  {
  	/*
  	 * Grab cpu pointer in each case to avoid spurious
  	 * preemptible warnings
  	 */
  	switch (action & ~CPU_TASKS_FROZEN) {
  	case CPU_STARTING:
  		msm_local_timer_setup(this_cpu_ptr(msm_evt));
  		break;
  	case CPU_DYING:
  		msm_local_timer_stop(this_cpu_ptr(msm_evt));
  		break;
  	}
  
  	return NOTIFY_OK;
  }
  
  static struct notifier_block msm_timer_cpu_nb = {
  	.notifier_call = msm_timer_cpu_notify,
  };
  
  static u64 notrace msm_sched_clock_read(void)
  {
  	return msm_clocksource.read(&msm_clocksource);
  }
  
  static unsigned long msm_read_current_timer(void)
  {
  	return msm_clocksource.read(&msm_clocksource);
  }
  
  static struct delay_timer msm_delay_timer = {
  	.read_current_timer = msm_read_current_timer,
  };
  
  static void __init msm_timer_init(u32 dgt_hz, int sched_bits, int irq,
  				  bool percpu)
  {
  	struct clocksource *cs = &msm_clocksource;
  	int res = 0;
  
  	msm_timer_irq = irq;
  	msm_timer_has_ppi = percpu;
  
  	msm_evt = alloc_percpu(struct clock_event_device);
  	if (!msm_evt) {
  		pr_err("memory allocation failed for clockevents
  ");
  		goto err;
  	}
  
  	if (percpu)
  		res = request_percpu_irq(irq, msm_timer_interrupt,
  					 "gp_timer", msm_evt);
  
  	if (res) {
  		pr_err("request_percpu_irq failed
  ");
  	} else {
  		res = register_cpu_notifier(&msm_timer_cpu_nb);
  		if (res) {
  			free_percpu_irq(irq, msm_evt);
  			goto err;
  		}
  
  		/* Immediately configure the timer on the boot CPU */
  		msm_local_timer_setup(raw_cpu_ptr(msm_evt));
  	}
  
  err:
  	writel_relaxed(TIMER_ENABLE_EN, source_base + TIMER_ENABLE);
  	res = clocksource_register_hz(cs, dgt_hz);
  	if (res)
  		pr_err("clocksource_register failed
  ");
  	sched_clock_register(msm_sched_clock_read, sched_bits, dgt_hz);
  	msm_delay_timer.freq = dgt_hz;
  	register_current_timer_delay(&msm_delay_timer);
  }
  
  static void __init msm_dt_timer_init(struct device_node *np)
  {
  	u32 freq;
  	int irq;
  	struct resource res;
  	u32 percpu_offset;
  	void __iomem *base;
  	void __iomem *cpu0_base;
  
  	base = of_iomap(np, 0);
  	if (!base) {
  		pr_err("Failed to map event base
  ");
  		return;
  	}
  
  	/* We use GPT0 for the clockevent */
  	irq = irq_of_parse_and_map(np, 1);
  	if (irq <= 0) {
  		pr_err("Can't get irq
  ");
  		return;
  	}
  
  	/* We use CPU0's DGT for the clocksource */
  	if (of_property_read_u32(np, "cpu-offset", &percpu_offset))
  		percpu_offset = 0;
  
  	if (of_address_to_resource(np, 0, &res)) {
  		pr_err("Failed to parse DGT resource
  ");
  		return;
  	}
  
  	cpu0_base = ioremap(res.start + percpu_offset, resource_size(&res));
  	if (!cpu0_base) {
  		pr_err("Failed to map source base
  ");
  		return;
  	}
  
  	if (of_property_read_u32(np, "clock-frequency", &freq)) {
  		pr_err("Unknown frequency
  ");
  		return;
  	}
  
  	event_base = base + 0x4;
  	sts_base = base + 0x88;
  	source_base = cpu0_base + 0x24;
  	freq /= 4;
  	writel_relaxed(DGT_CLK_CTL_DIV_4, source_base + DGT_CLK_CTL);
  
  	msm_timer_init(freq, 32, irq, !!percpu_offset);
  }
  CLOCKSOURCE_OF_DECLARE(kpss_timer, "qcom,kpss-timer", msm_dt_timer_init);
  CLOCKSOURCE_OF_DECLARE(scss_timer, "qcom,scss-timer", msm_dt_timer_init);